The overall goal of our research is to develop novel drug delivery methodologies for treatment of lymphatic cancer and other conditions involving lymph nodes. Hypothetically, there are two molecular mechanisms that can facilitate transport of macromolecules from the blood to lymph nodes; both depend on specific carbohydrate structures present in the macromolecules. The fast, dose-dependent Type I uptake most likely relies on an abrupt and specific opening of the endothelial barrier in the lymph nodes, followed by extravasation and uptake of the macromolecules. The slower, dose-independent Type II uptake likely includes receptor-mediated transendothelial transport in the tissues outside the nodes with subsequent drainage to the nodes through the lymphatic vessels. In both cases, lymph nodes accumulate very significant levels of the administered material; e.g., lymph node: muscle ratios for type I and Type II at 1 hour after injection were 11:1 and stable and 25:1 and growing, respectively. We further hypothesize that both mechanisms can be combined to rapidly deliver even higher doses of drugs or drug carriers to lymph nodes. The objectives of this exploratory study are to determine: (1) whether the routes of the Type I and Type II uptake in the nodes are direct (through the vascular endothelium of lymph nodes) or mediated by extravasation elsewhere followed by delivery to the nodes through lymphatic vessels; (2) what carbohydrate structures of the macromolecules participate in the systemic lymphatic uptake and what cells in the nodes accumulate the respective type; and (3) whether type I molecules activate only their own intranodal extravasation at high doses or they can facilitate systemic delivery of other molecules to the nodes. Impact.The proposed study will provide key data on the mechanisms of systemic lymph node targeting with glycoconjugates, which will open the way for the development of systemic therapeutics for lymphatic cancer and other conditions involving lymph nodes (potentially, AIDS and other immune system disorders).